form_fieldtype(3X)                SDK R4.11               form_fieldtype(3X)


NAME
       form_fieldtype:  new_fieldtype, free_fieldtype, set_fieldtype_arg,
       set_fieldtype_choice, link_fieldtype - forms fieldtype routines

SYNOPSIS
       #include <form.h>

       FIELDTYPE *new_fieldtype(int (* field_check)(FIELD *, char *),
            int (* char_check)(int, char *));
       int free_fieldtype(FIELDTYPE *fieldtype);
       int set_fieldtype_arg(FIELDTYPE *fieldtype,
            char *(* mak_arg)(va_list *),
            char *(* copy_arg)(char *), void (* free_arg)(char *));
       int set_fieldtype_choice(FIELDTYPE *fieldtype,
            int (* next_choice)(FIELD *, char *),
            int (* prev_choice)(FIELD *, char *));
       FIELDTYPE *link_fieldtype(FIELDTYPE *type1, FIELDTYPE *type2);

DESCRIPTION
       new_fieldtype creates a new field type.  The  application  programmer
       must write the function field_check, which validates the field value,
       and  the  function  char_check,  which  validates   each   character.
       free_fieldtype frees the space allocated for the field type.

       By associating function pointers with a field type, set_fieldtype_arg
       connects to the field  type  additional  arguments  necessary  for  a
       set_field_type  call.  Function mak_arg allocates a structure for the
       field specific parameters to set_field_type and returns a pointer  to
       the  saved  data.  Function copy_arg duplicates the structure created
       by make_arg.   Function  free_arg  frees  any  storage  allocated  by
       make_arg or copy_arg.

       The  form_driver requests REQ_NEXT_CHOICE and REQ_PREV_CHOICE let the
       user request the next or previous value of a field type comprising an
       ordered  set  of values.  set_fieldtype_choice allows the application
       programmer to implement these requests for the given field type.   It
       associates  with  the  given  field  type  those  application-defined
       functions that return pointers to the next or previous choice for the
       field.

       link_fieldtype returns a pointer to the field type built from the two
       given types.  The constituent types may be any application-defined or
       pre-defined types.

RETURN VALUE
       Routines  that return pointers always return NULL on error.  Routines
       that return an integer return one of the following:
       E_OK           - The function returned successfully.
       E_SYSTEM_ERROR - System error.
       E_BAD_ARGUMENT - An argument is incorrect.
       E_CONNECTED    - Type is connected to one or more fields.

NOTES
       The header file <form.h>  automatically  includes  the  header  files
       <eti.h> and <curses.h>.

SEE ALSO
       curses(3X), forms(3X).


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